1. Technical Field
The subject invention relates to monoclonal antibodies and uses thereof.
In particular, the invention relates to three monoclonal antibodies, referred to as B1, B3 and B5, which are useful in the treatment and diagnosis of many forms of cancer.
2. Background Information
Current therapies for metastic human cancers, such as radiation or chemotherapy, center on agents that selectively kill rapidly growing cancer cells. Unfortunately, many tumors do not show an unusually fast growth rate compared to important normal tissues, such as bone marrow or the epithelium of the gastrointestinal tract. An alternative group of therapeutic approaches targets unique chemical structures on the surface of tumor cells for therapy, most often employing antibodies that bind selectively to these target molecules. One of these therapeutic approaches employs antibodies that are coupled to cell-killing agents, such as plant or bacterial toxins. These antibody-toxin complexes, immunotoxins, have been shown to be capable of selectively killing tumor cells in model tumor systems in tissue culture and in laboratory animals (Pastan, et al, Cell, 47:641-48 (1986)). In spite of many attempts to isolate such tumor-specific antibodies for human therapy, there are still very few antibodies identified that selectively bind only to tumor cells and not to other important normal tissues. Isolation of such tumor-specific antibodies is, therefore, of importance for the application of such immuno-directed therapies.
Monoclonal antibody methodology as originally described by Kohler and Milstein (Nature 156:495-97 (1975)) and disclosed in Koprowski, et al. (U.S. Pat. No. 4,172,124) has allowed the isolation of antibodies in pure form for the construction of therapeutic agents. However, two problems have prevented the application of many previously isolated antibodies. First, many monoclonal antibodies reactive with tumor cells also react with important normal human tissues. Secondly, many of the isolated antibodies bind to surface elements that do not efficiently mediate the entry of toxin conjugates into cells by endocytosis. The present invention includes three monoclonal antibodies, B1, B3, and B5, that selectively bind to some human tumors, but not to many important normal tissues. These antibodies, when incorporated as the targeting element of an immunotoxin, also have been shown to allow efficient entry of these toxic agents into cells.
Previously, antibodies reactive with the Lewis Y antigen have been isolated and characterized. Recently, two antibodies, BR64 and BR96 have been described (Hellstrom et al., Cancer Res., 50:2183-90 (1990)) that react with Lewis Y antigen, one of which (BR64) is not useful for immunotherapy because of its reactivity to capillaries in human cardiac muscle. BR96, however, shows reactivities that might make an immunotoxin constructed with this antibody potentially useful. The three new monoclonal antibodies, B1, B3, and B5, referred to above, which were isolated using a different cell type for immunizations and using morphologic screening methods, are similar, but not identical, to BR96. These differences in reactivity to tumors, normal tissues, and carbohydrate epitopes make these three new antibodies potentially useful for the therapy and diagnosis of some forms of human cancer.